For months now, Israeli Prime Minister Benjamin Netanyahu has been at the center of a corruption investigation. And now, there's a big development. Netanyahu's former chief of staff has struck a deal with authorities to become a witness for the state. All this, of course, is now raising questions about Netanyahu's political future. NPR's Daniel Estrin is on the line now from Jerusalem. Hey, Daniel.

DANIEL ESTRIN, BYLINE: Hey, Rachel.

MARTIN: What is Netanyahu suspected of doing?

ESTRIN: Well, police say they're investigating possible fraud, breach of trust and bribery. And we're talking about two main corruption investigations involving Netanyahu. What I can tell you about them comes from Israeli media reports. So case number one reportedly involves suspicions that Netanyahu got expensive gifts like champagne - pink champagne, cigars from an Israeli Hollywood producer, one of the producers of "Pretty Woman."

And the police are also - they're looking at whether those gifts amount to bribery because there are reports that Netanyahu asked then-Secretary of State John Kerry to help get the Israeli producer a long-term U.S. visa. So then there's another case involving a secret deal - allegedly - where Netanyahu tried to get positive press coverage for himself in a major Israeli newspaper by offering to help undercut the newspaper's competitor. And that is where Netanyahu's former chief of staff plays a major role.

MARTIN: OK. Tell us about this this guy.

ESTRIN: Yeah. His name is Ari Harow. And I want to play you a short clip of a recent Israeli television news story about him just to give you a little flavor of how he's being portrayed here with some, you know, ominous music.

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UNIDENTIFIED JOURNALIST: (Speaking Hebrew).

ESTRIN: So he's kind of like this mystery man here. He stayed in the shadows, but he was a very close confidant of Netanyahu. I spoke to this political commentator, who said Ari Harow was like a son to Netanyahu. He reportedly got in trouble for running his own consulting company while working for Netanyahu. And while police were investigating that, they reportedly found some iPhone recordings Harow made of Netanyahu's conversations with that newspaper publisher I was speaking about earlier.

So what we do know is that the authorities have made a pact now with Ari Harow. He will plead guilty and get a reduced sentence for the separate case involving reportedly his consulting company. And then in exchange, he'll provide testimony in the Netanyahu corruption cases.

MARTIN: Wow. So former chief of staff could be turning against his old boss it sounds like. So what does all this mean for Netanyahu, his political future?

ESTRIN: Yeah. That's the big question people are asking here. He - you know, Netanyahu, he's the longest-serving prime minister here since Israel's founding father. And if you go to Netanyahu's Facebook page, he says he's done nothing wrong. He's staying in his seat. He sees this - he's portrayed this as something that's not about him personally but a left-wing media attempt to topple his right-wing government.

The question here is if Netanyahu is charged with a crime, would he have to step down? And the answer is technically no. Although the previous prime minister here stepped down when he faced his own corruption investigations. So Netanyahu would likely face that kind of pressure. And the timeline here, Rachel, it probably - if Netanyahu does get charged, it would take months and maybe more than a year.